Existing electrical machines provide the ability to capture power from a mechanically rotating source, such as a wind turbine or deliver power to load such as a pump or compressor. A synchronous machine may therefore comprise a synchronous motor or a synchronous generator. As an example, a synchronous motor includes a stator, which carries an armature winding, and a rotor, which carries a field winding and which rotates at a supply frequency or a submultiple of the supply frequency. The armature winding is spatially distributed for poly-phase alternating current (AC), which creates a rotating magnetic field inside the synchronous motor. The magnetic field on the rotor is either generated by current delivered through slip rings and brushes to the field winding of the rotor or by a rotor comprised of a permanent magnet. On excitation through carbon brushes connected to slip rings on the rotor shaft, the field winding behaves as the equivalent of a permanent magnet. A drawback to synchronous machines utilizing brushes and slip rings is that the slip rings and brushes present reliability and maintenance issues because they are often a source of mechanical failure. Conversely, embodiments utilizing a permanent magnet are becoming increasingly expensive due to the scarcity of the raw materials used to form the permanent magnet.